Page 169 - Handbook of Structural Steel Connection Design and Details

Design of Connections for Axial, Moment, and Shear Forces

154 Chapter Two

Block shear on plate

1
A nt 5 t p cL e 2 0.5a h 1 bd
16
1
5 0.5c2 2 0.5a1.3125 1 bd 0.656 in 2
16
A gv 5 t [L 1 sn 2 1db] 5 0.5[1.5 1 s7d3] 5 11.3 in 2
e
p
1
A nv 5 t cL 1 sn 2 1db 2 sn 2 0.5da 1 bd
p
e
h
16
5 0.5[1.5 1 s7d3 2 s7.5ds1.125d] 5 7.03 in 2
R bs 5 s0.6F A nv 1 U F A d # s0.6F A gv 1 U F A d
nt
y
nt
u
bs u
bs u
5 0.75[0.6s65ds7.03d 1 1.0s65ds0.656d]

5 238 # 0.75[0.6s50ds11.3d 1 1.0s65ds0.656d] 5 284
5 238 kips $ 150 kips, ok
It is generally assumed that beams are torsionally supported at their
ends. Lack of torsional support can substantially reduce the flexural
capacity of beams that are otherwise laterally unsupported. Generally,
the torsional stiffness of end connections to beams that are fully braced
by a diaphragm, such as a slab or a deck, is not an issue. However,
though the AISC Specification does not contain a check for torsional stiff-
ness, end connections for beams that are not laterally supported should
be checked. The check presented here is based on Australian require-
ments, which assume lateral support only at the applied mid-span load.
Assuming the W30 90 has a span of 28 ft:

J b d 2
f
k $ 448000 c1 1 a b d
s
L t L
f
3730s24ds0.5d 3 2.84 s10.4ds29.5d 2
$ 448000 c1 1 a b d
9.0 336 s0.610ds336d
kips-in kips-in
1240 , 12300
radian radian
Therefore, the beam cannot be considered to be torsionally restrained
by the extended shear tab.
In order to provide sufficient torsional restraint, the shear tab thick-
ness would need to be.

12300s9.0d
t p 5 3 5 1.07
B 3730s24d

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